The present invention relates to metallocene catalyst systems for the polymerization of C.sub.2 -C.sub.10 -alkenes, obtainable by deactivating a preactivated metallocene catalyst system which contains, as active components, a metallocene complex of a metal of subgroup IV or V of the Periodic Table and an oligomeric alumoxane compound.
The present invention furthermore relates to metallocene catalyst systems obtainable by reactivating the deactivated metallocene systems, processes for the preparation of the deactivated and reactivated metallocene catalyst systems, their use for the preparation of polyalkenes, processes for the preparation of polyalkenes with the aid of these metallocene catalyst systems and the polyalkenes obtainable.
Since metallocene catalysts obtain optimum polymerization activity when they are preactivated with aluminum compounds, process engineering problems, for example blockage of the metering system due to premature polymerization, may occur during metering of the catalysts. This problem can be avoided by deactivating such catalyst systems, although the deactivation must be reversible.